Telephone-exchange system



Jan. 4 1927. 1,613,246-

' H. W. ONEILL TELEPHONE EXCHANGE SYSTEM Filed Nov. 15, 1922' 3Shqets-Sheet l five/70 Henry W OA/e M Jan. 4, 1927. H. w. ONElLLTELEPHONE EXCHANGE SYSTEM Filed Nov. 15. 1922 3 Sheets-Sheet 5 Henry WO/Ve/H ii. a e

HENRY W. ONEILL, OF BROOKLYN, NEW YGRK, ASSIGNOR TO WESTERN ELECTRICCGMPANY, INC-OREORATED, OF NEW-YORK, N. Y., A COBlOEATION-UF NEW' YGRK.

TELEPHONE-EXCHANGE Application filed November 15, 1822. Serial No.601,016.

This invention relates to a telephone exchange system, and moreparticularly to a system in which toll connections are establishedbetween exchanges by means of machine switching equipment controlledover toll lines.

{)ne of the objects of the invention is to improve the manner ofestablishing connections in systen'is of this nature.

A further object of the invention is to improve the control of automaticswitches by impulses of alternating current over toll lines.

T o attain the objects of the invention the outgoing end of a toll lineextending from a toll operators position to a machine switching officeis provided with means for effecting current changes in the toll line toenergize an electromagnetic devic associated with the incoming end ofthe toll line.

This device in operating; prepares switches at the automatic otlice forthe reception of impulses. The operator may thereupon actuate her dialthereby a iplying' alternating current of a frequency preferably withinthe voice range to the toll line, which current is transmitted to thedistant ofiice, Where a responsive device controls the setting of theswitches at the automatic office in accordance with the digits dialed bythe operator. The operators cord circuit is provided with a supervisorysignal which is actuated when the called subscriber answers when hehangs up his receiver and when he flashes so as to provide fullsupervision for the operator.

These and other features of the invention will be more readilyunderstood by reference to the accompanyingdrawings in which Figs. 1 to4, inclusive, when taken together show partly in full and partlyschematically the circuits involved in building up a con nection betweena subscribers station through a toll operators position over a toll lineto a subscribers station at a distanteirchange; Figs. 5 and 6 show amodified form of the toll line shown in Figs. 2 and 3; and F i g. 7shows a cord circuit arranged for supflying direct currents as well asalternating currents for automatically establishing a connection over atoll line, and a toll line cquipn'ient suitable for use therewith.

In general. and referringmore particularlv to Figs. 1 to it, inclusive.the system functions in the following manner: A subscriber in the first.exchange desiring connection with the subscriber in the distant exchangewhich may be reachec directly from the first exchange over the toll lineT, first obtains a. connection, through the position of the usual A oranswering operator, with toll operator. After receiving instructionsfrom the calling subscriber through the A opcrators position, the tolloperator obtains a connection with the calling line over a tollswitching trunk and extends the connection by means of her callinc" plugto an idle toll line such as toll line T extending to the desireddistant exchange. In response to the seizure of the toll linealternating; cur rent of a frequency of approximately 700 cycles,inon'ientarily connected to the toll line to energize an electromagnticdevice normally bridged across the incoming end of the toll line toprepare automatic switching apparatus associated with the incoming endof the toil line for the reception of dialing impulses. The tolloperator then proceeds to transmit dialing impulses over the toll lineby the application of alternating current of a frequency of an'iroxiii'iately 700 cycles to the toll line. These impulses actuate theelectromagnetic devices at the incoming end of the selected toll. lineand are translated into direct current impulses and repeated to theautomatic switching apparatus accessible to the toll line. Through theoperation of the electromagnetic device at the incoming; end of the tollline and the automatic switches, the connection is then extended to thedesired. line in the distant exchange. Ringing; current is then appliedautomatically to the line of the called station in the usual manner bythe automatic switching equipment. When the called subscriber answers.currents of two frequencies, preferably within the voice range, aremomentarily applied to the incoming end of the toll line. At theoutgoing end of the toll line these currents are translated to effectthe control of a supervisory signaling device.

Upon termination of the conversation and restoration of the receiver tothe switchhook at the substation of the called subscriber in the distantexchange, currents of two frequencies are applied to the toll line atthe incominnnend which currents are translated at the originating; eiidof the lineinto a supervisory signal to indicate that the COtlTleC-tied? truly is taken down l l bei'i the nrip} llt at u

'ClHiE 5c. The toll operator then seltats idle toll line extending tothe dist-11st er: change, the busy toll lines of the group 0- tending tothis c: ;change being; unt l-zed l busy potential upon the Sl'C-CYQH oithe jucx of these lines. it will be assumed that t line 'l disclosed inthe drawing 's idle at hinting): toll operator withdraws the plug ol hercord circu t from the jacl: ot the toll line. an impulse 0t alternatingcurrent is etective to restore the apparatus at the automatic exchangeto normal.

ll? the suhscriloer at the called station flashes in'ipnlses ofalternating current will be returned to flash the supervisory signal inthe ope 'at-ors cord circuit at the originat ng: exchange to indicate tothe operator that the called station desires further attention.

The electromagnetic devices employed in this invention are such thatwhen they are energized by alternating currents, preten ably within thevoice oil fretpiencies they open taeir contacts. These contacts re mainopen until the current flow throng; t the device ceases. Such devicesmay he of he type employing an inertia ineiuher n'hic may be acceleratedby alternating current shown in Patent No. 1507310, granted i veniher223, 1926, to H. H. (l llcill, either it is to he understood that theinvention not limited to the type ot the device disclosed in saidpatent.

Having now outlined in a general manner the system and described brieflythe nature of the apparatus employed, it is believed that a clearunderstandin3;- ot the invention may he had from the following detaileddescription of the method of extending a connection from the st 'ion Aat a change through a toll operators position, and over a toll line to asubscribers station 13 at a distant automatic otllcc in which the toll lne terniiinates.

It will he assumed that the operator at the toll positioi hasestablished a connection n'ith a suhscribefs station It over a tollswitching trunk in any manner Well l-I11()Yr'll in the'art} and hasascertainml that the subscrih r at station A (l "res conncctio 'Y 1 lthe subscriber at stat on at; the dis-an s theretoie the operatorinserts a pl cord crcu t C into the pic 0? this lane,

1 thereupon completed ove a ran circuit is i ei-itendin u from ground,throt'rgh the \"ltt ing' of relay (3, sleeves o'l jacl; Z and plug theupper winding and lower contact of relay 32. and thence through theiarallel connsch ed local contacts o'l alternating' current rclays 2t)and ill) to grounsilcd hattrry. Relay is in operating closes itscont-acts l? betore contacts 16 open and energ zes relay over an obyioutcircuit. Alternating current from the source 22 is thus momentarily cnected to the talking conductors 25 and 2o and to toll line 'll illlOlt-Ifill the contacts 40 and l. otrelay 4:8 and cont; cts and l?! of relayl'z), in order to encr -e the electromagnetic device 200 WlllCll isnormally bridged across the incoming end of the t ill line T e ininterval th distant exchange. the contacts 17 of relay 6 close. the conirelay 6 open thereby releasing aerated slorvto release relay 4' 8.releasingnow renders the tall:-

s of the Olltll'Ollll end of the :outnionn ant disconn the ternatingcurrent from the a an olwious p .i accessible to the inceinil gr end otthe l tor the reception oat impulses. t will he noted tiat relay 250 isnormally operated. over a path extending from grounded hattery, throughthe vinding of relay 250, contacts 451 of relay thence through thecontacts 201 oi device 200, and thence throi gh the contacts of relay toground. l elay 250 is marginal and releases in series with highresistance relay which operates when the contacts 20L of the device linl opened. Relay 250 in retract ng upper ar nature closes the loop acrossthe conductors F0 and 261 extending from conductor s Winding 0t relay262, rind i1 of relay 365, contacts of relay and uppermost contacts ofrelay .2 to the ring conductor 261.

The closure ol the loop acro s the end of the line to which theaul'ounnic gwltche are accessible causes the energizaation oi the linerelay 2T0 associated \Yllll the selector switch S and, ot the relay inthe loop circuit. he line relay 3Y0 in o 'ieratiug causes the operationof relay \rhicu places a ground upon the third conductor, 271 whichground causes the euergization o l relay Relay 252 in operating closesthe ilollowing substitute loop across the line; 't'roui tip conductor26%, through the w nding of relay Winding: of relay 255, contacts $380of relay the contacts 1,)" ol? device 200 contacts 281 of relay to theri e; conduct;- or 261'. The closure ot' the contacts E35 o't' relay 272operates relay 350 over an ()lJYlous circuit to apurpose to he describedla ter. Relay 262 is energized in the circuit traced but relay is notenergized since the latter relay is oil' the polarized type and thedirection of tlow of current through its Winding}; at this time not suchas to cause its operation. .Vhen relay 250 released, the passing contactassociated with its lower armature causes a momentary response of relay2%, which applied momentarily,"alter nating current from the sources 291and 292 through the transformers 218 and 219 and the upperand loweralternate contacts of relay 290 to the talking conductors of the lineand connected cord circuit.

The talking and dialing key 72 now-in its actuated position preparatoryto the operation of the dial, such currents are manifested in theoperators set as a dialingsig-- nal. That is, lamp 8 is extinguished andit should be understood that on the reoperation of relay 250, lamp 8 1Sagaln lighted.

JV l 'lhus, tee dialing signal consists oi the momentary extinguishingof lamp 8- and it will become apparent as the descriptionproceeds howthe operation of the relays in the cord circuit will efl'ect this resultin response to the n'ioinentaryrelease of relay 250.

The operator thereupon *actuates the dial D to send a number of impulsescorresponding to the digits in the number desired. As

thedial is rotated ofl normal, the primary-- winding of the lnductioncell in the -opera-" tors set is switchedfrom the transmitter to asource 77. Thls 1S accomplished by the opening-0t contacts St and theclosure of contacts 87 of the dial. The opening of contacts also removesa shunt to permit the operation ofhighdmpedance relay 75 in the primarycircuit of "the operators set) The operation of relay 7 5 disconnectsthe operators receiver and connects the normally closed pulsing contacts73st the-dial in bridge of the secondary winding ofthe' induction coilof the operatorisset.

"Upon the return movement of the dial each separation of the pulsingcontacts 73* permits an impulse ofalternatmg current from thesource 77to traverse the cord-and line circuits and effect the response of theelectromagnetic device 200.

In responding to these impulses the electromagnetic device 200 opens itscontacts 201 in unison with the interruptions atthe' dial D causingthereby the interrupted opening of the loop across the conductors260and- 261. y

The resistance of the Winding-of relay 254 bridged across the contacts201 is 'sui'liciently high to permit'the release of pulsing relay-270 ofthe switch S. Relay 25 1 is adapted to continue energized during thereception of: a series of alternating-current impulses by device 200,thereby disconnecting ground to render responses of relay 262 tointerruptions of the loop circuit iue'liectiveat this time with respectto rolav 220.

Under control-of device-200 the selector switch S advances to selze theconnector 1 switch K following which the pulsing relay 270 and releaserelay 272 willbe disconnected, and a pulsing relay 294*andrelease-relaytut'ed therefor inthe usual manner.

ing of relay 32.

fer from its lower to its upper contacts.

-relay"32 to the sleeve conductor.

295 of the connector switch will be substi- Further operation of thedial will cause connector K to seize the terminals of the line leadingto station E whereupon ringing current Will be automatically applied bythe connector K to signal station E.

' When the called subscriber answers, the

line relay 299 will be operated over an obvious path therebyreversingthe How of current over the conductors 260' and 261, andcausing the operation of the polarized relay'265. Relay 265 in operatingopens its contacts 298 to disconnect the device 200 and closes itscontacts 296-and 297 thereby electrically joiningthe toll line with bemain I conductors through the automatic switches.

hen the current is reversed over the conductors 260 and 261, relay 262releares mo-- mentarily and closes its passing cmitacts again causingthe ener lzation of relay .390

and the application of the'alternating currents from Oll1'C-6S 291 and292 to the line. The'tlppllCtttlOll Of the alternating current at thistinie energizes the electron agnetic devices 20 and 30 bridged acrossthecord circuit, to extinguish supervisory lamp 8. At the time the plug4 was inserted in pick 5 current "from grounded battery,as previousltraced throu 'h the u oer winding and u D a,

lower contact of relay 82, serves to shunt relay 18. Therefore, batteryflowing through the normal contacts o't' the latter relay, the windingof relay 10 and the low r winding of relay 32 to thesleeve conductor,energizes 'relay 10 to cause the illuminationot super v1sory lamp 8 andalso to'disconnect relay 18. The'operation 01 devices 20 andSi') inresponse to" the impulse of current transteam upon the answer ofstation- B,

disconnects battery from the upper wind- This permits the currentflowing through the lower winding of relay 32 over the path alreadytraced to-move the a ri'nature of this relay to trans- On Cessationotthe incoming alternating currentsand the resultantrestoration ofdevices 20 and 30, grounded battery applied to the upper contact ofrelay 32 through its armature shunts relay'lO to effect its release toextinguish lamp 8. The normal position of relay Relay 262 again closesits passing pal contacts and energizes the relay 290 to again applyalternating current from the sources 291 and 292 to the trunk circuit toenergize the devices and bridged across the cord circuit. The resultingcessation of current flow through the lower winding of r lay permits thecurrent present already "traced through the upper winding of this 1 plug4- :Erom the jack whereupon relay 6 releases operating relay 48 andreleasing re the toll line.

lay 49. The quick operating characteristic of relay 4L8 comhineo withthe slow releae characteristic of relay ll) permits an impulse ofcurrent to flow from source 22 over the line. The final release of relay49 disconnects the source 22.

When relay 265 released, following; the restoration of the receiverstation B, in addition to the disconnection oi the line from the mainconductors of the automatic switches, the device 200 was reconnected toThe impulse of alternating current changes the resistance of the loopcircuit so as to permit the restoration of release relay 295 ofConnector K. The resulting removal of groundirom conductor 271 permitsthe restoration of relay 252, thereby switching the circuit of relay 250by way of contacts 201 of device 200 to ground at the normal contacts ofrelay The slow release of relay 250 permits it to hold during thisoperation and prevents ro-selzure of the loop circuit and prevents anye'tl'cct at this time with respect to relay 290.

It, during an. cstaolished connection, the called. subscriber flashes,relay 2% will alternately dccnergl'imi and cnci ze thereby causing theintermittent actuation oi the devices 20 and 30 oi": the cord circuitand the consequcnt [lashing of the lamp 5- Lamp 5% will be lighted andestinguishcd in the manner pre viously described and the operattunotthis flash may actuate her listening key to inquire what the calledstation desires.

Figs. 5 and 6 show a modification ot' the toll line whereby anoriginating operator n'iay release the distant automatic suitchesirrespective of whether the receiver has been returned to its switchhoohat a called station. In this arrangement. upon the insertion of plug 4of cord circuit- C in jack 5 ct Fig. 5, the response of relayscorrespondingly numbered with respect to relays of Fig. 2, will takeplace to apply to the line an impulse formed of alternating currentsfrom sources and ll At the distant equipment shown in Fig. 7 the device200' responds to the current of TOO-cycle frequency flowiin from source4C5, the current of lfiOO-cycle i'requency being without materialc'il'ect at this time. It will be noted that device 2 0 tuned forresponse to current or" lfitlO-cyclc frequency is normally shuntedthrough contacts 298 of relay 265. The response of device 200 causes aseries of operations to take place similar to that described inconnection with Figs. 1 to l, inclusive, whereby a connection isestablished between the toll line and the called station Qu response oi?the called station and the consequent operation of relay 265, the

hunt around device 240 is removed to bring 'uch device in series withdevice 200 across he main conductors of the line. Closure of contacts 2-2 of relay 265 establishes the contacts 2-ll of device 240 in parallelwith the contacts 201 of device 200. This condition obtains during anestablished connection in order to insure that tuned devices 200 and 240may not jointly respond to voice currents. In the case of a separateresponse of either device the other device will be inert and therebymaintain the connection. Further protection against premature release ofthe connection is also provided through the slow releasecharacterist-ics of the regular holding relay of the automatic switchessuch as relay 272 or relay 295. Supervisory effects take place in amanner similar to'that described in connection with Figs. 1 to 4.

Assuming that the operator desires to release the connection betore thereceiver has been restored to its switchhook at station B, the removalof the plug t from jack 5 results in the response of relays in Fig. 5 toapply an impulse of current from sources 45 and 46 to the toll line. Thejoint response of correspondingly tuned devices 200 and 24 0 serves tochange the resistance in the direct current loop circuit, therebyoilecting the release of the autonuitic switches in a manner similar tothat previously described for similar switches of Fig.3. In case thereceiver has been restored at the called sta lion and relay 265 therebyreturned to its normal condition, separation ol its contacts 242disconnects contacts 2-H, of device 21!) which will. then stand shuntedthrough the normal contacts 298' ct relay 265'. There fore. the impulsevof current resulti g from the removal of plug 4 from jack 5 will coutroldevice 200. Response of such device will release the connection asdescribed in connection with the arrangement shown in Fig. 3.

The cord circuit shown in Fig. 1 is also adapted to control switchesover a direct current loop as in extending a connection by lit) way of atoll switching trunk to the line of a calling station, such as stationA. In the dialing position, the talking key actuated and the dial Dmoved from its normal position, the pulsing contacts 73 will be connected by way of the forward contacts of relay 75 in bridge of the mainconductors of the cord circuit. At each interruption of contacts 73during the return of the dial the direct current loop which may beassumed as extending froin'the automatic switching apparatus leading tothe station A, will be opened due to the presence of condenser 90inserted in series with the secondary winding of the operators inductioncoil, since relay 7 5 is operated. These impulses control the switchesin a well known manner. During periods intermediate successiveoperations of the dial while the dial is in its normal condition, thereleased condition of relay 75 in addition to reconnecting the operatorsreceiver also shunts condenser 30 to provide a direct current paththrough the secondary winding of the operatofls ind netion coil to holdthe automatic switches.

Atter the dialing is completed and the talking key 72 is restored, theautomatic switches involved in the connection to station A will beretained by a direct current bridge which includes the seriallyconnected devices 20 and 30 and relay 99 and the normalcontacfs oi? key72. Relay 99 controls the supervisory lamp 100 under reversals ofcurrent in the direct current loop efiected by the supervisory efiectscontrolled by the substation A.

Combined dialing and splitting' keys 95 and 96., respectively serve toseparate the cord circuit. During periods the key 9? may be in itsactuated position, its outer contacts will establish the supervisoryrelay 99, across the end of the cord circuit connected with station Afor holding and supervisory purposes. In such a case the operatorstelephone set will be available'by way of the key T2 for talking ordialing over the toll line. In an inverse manner key 96 in an actuatedposition applies devices 20 and 30 across the toll line while theoperators set may in a similar manner be connccted for dialing orconversing with. respect to station A.

A description oi the operation of Fig. will now be given. Thiscombination presents a modification of the arrangement shown in Figs. 1to 4, inclusive, the modification consisting of preparingthe switchesfor reception of impulses and controlling the supervision over the trunkline by direct current instead of alternating current. It will beassumed that the operator at the toll position has answered andestablished a connection through the jack 300 and the plug 301 with thesubstation A in any manner well known in the art and ascertained "fromthe subscriber at substation A that a connection with substation B isdesired.

In establishing'the connection with'call ing station-A the plug 301 ofcord circuit C is inserted in jack 300 01": a toll switching trunkassociated with automatic switches not shown. A splitting key 320 isactuated to disconnect the equipment associated with plug 305. Talkingkey 321 is actuated and dial D operated. When the dial moves oil normal,relay 3&3 operates over an obvious circuit to disconnect the operatorstelephone set and to connect the pulsing contacts 01 the dial in serieswith slowto-release relay 322 in bridge of the cord circuit. The latterrelay responds to the direct current supplied to the trunk circuit bythe automatic switches to disconnect the alternating current source 351.ct contacts 341 as the dial D returns to norand, controls the setting ofthe automatic switches upon the terminals of the line lead ing tostation A in a well known manner; \Vhen key 320 is restored the switchesare held by a bridge including repeating .coil 302 and relay 303. Relay303 controls lamp from station A.

Insertion oi the plug 305 into the jack 303 of the toll line B completesa circuit through lamp 307 over a path extending from grounded battery,through lamp 307, resistance 303, sleeve ot plug 305 and Jack" 300 andresistance 309 to ground; The inseriion of the plug 305 into jack306"also completes thefollowing circuit: grounded battery, winding ofrelay-310, lower righthand winding of repeating coil 302, rings of plug305 and jack 306, in'lpedance coil 41-01,

left-hand high resistance winding of relay 4.00, tips of jack 306 andplug 305 and upper right-hand winding-0t repeating coil- Relay 310 is ofmarginal across the conductors 410-and 4-11 causes the energization ofthe line relay (not shown) of the selector swltchin the manner wellknown 1n the art.

The operator may then proceed to dial; Theactua-tion of the key 350disconnects the trunk side of the connection, the switches of winch areheld by the brldge including relay 323. Lamp 325 under control of relayO l to give supervisory signals transmitted Relay 400 energizes,however, in this Successive interruptions 1 323 prevents isolation ofcalling station A.

Theoperator then actuates the talking key 321.

The operator may thereupon actuate lil ill

dial D a number of times corresponding to the digits in the numberdesired. Relay 822 does not operate at this time since no direct currentis now present in the dialing loop. Upon the return movement of the dialto normal position the contacts 341 are interrupted a number of timescorresponding to the digit dialed. The short circuit through thecondenser 327 of the alternating current source is opened each time thecontacts 341 of dial 1) are opened, thereby interruptedly applyingcurrent from the source 351 to the cord circuit. This current is inducedinto the secondary winding of repeating coil 302 and passes over theupper and lower talking conductors of the cireuit'E through the normalcontacts of relay 4-12 and the winding of the electromagnetic device420. The device 420 is ener ized by the alternating current applied toits windings, a number 01 times corresponding to the digits of thenumber dialed. During energization of the device 420 its contacts areopened thereby interrupting the loop across the talking conductors 4.10and ill. The setting of switches by interruptions in a loop circuit isan arrangement which is old and well known in the art and therefore adescription of the manner in which the selector switch S and connector Kare set will be omitted. A 'ter the connector K has been set, the calledstation 13 will be signalled in the manner well known in the art.

X Then the subscriber of the called station answers, relay 44:0 will beoperated over an obvious circuit thereby reversing the iiow of currentover the talking conductors 410 and 411. Polarized relay 412 will thenbe operated thereby opening its normal and closing its alternatecontacts. The opening of the normal contacts removes the device 420 frombridged relationship with the toll line and the closure of the alternatecontacts of relay L12 connects the low resistance right-hand winding ofrelay 400 across the circuit in parallel with the high resistancewinding of relay 00. Relay 310 of the cord circuit now operates inseries with the parallel connected windings of the relay L00. Relay 310in operating connects the resistance 360 in series with the resistance308 and lamp 307 is thereupon shunted. The extinguishment oi lamp 307indicates to the operator that the called party has answered.

Vl hen the called party restores his receiver to the switchhook, relay440 will deenergize and again cause a reversal of current over theconductors 410 and 411 thereby releasing the polarized relay 412. Relay412 in releasing disconnects the low resistance winding of relay 4:00fromthe circuit. Marsupervisory relay 310 releases its armature due tothe high resistance of the letthand winding of relay 400. Relay 310 inretracting its armature removes the shunt from lamp 307 whereupon saidlamp again lights to indicate to the operator that the called party hasrestored the receiver to the switchhook.

The operator may'thereupon remove the plug 305 from the jack 308,whereupon relay 400 will release thereby interrupting the loop acrossconductors 410 and 411. The opening of the loop circuit causes therelease ot the switches in the manner well known in the art.

In the cord circuits shown in Figs. 1 and 7, it is evident that althoughthe operators set will be disconnected during the actuated periods ofthe dial, it will, however,

be reconnected, when the dial is at rest. Therefore, any signals such asdialing, busy back and out oi order tones may become effective in thereceiver of such set.

ll hat is claimed is:

1. In a telephone exchange system, :1 called station, a source ofalternating current of a single frequency, means for transmittingimpulses from said source, electromagnetic means energized by saidalternating current impulses means controlled thereby and responsivewhen only a single frequency is transmitted for establishing aconnection with said called station, and means for giving supervisionback from the called station.

In a telephone exchange system, a first oiiice, a second ofiice, a lineextending between said oilices, a calling station at the first ofiice, acalled station at the second otiice, a source of alternating current ofa single frequency, means for transmitting impulses from said source,electromagnetic means energized by said alternating current impulse forestablishing a connection over the line between the calling and calledstations, and means for giving supervision back over the line.

In a telephone exchange system. a first oliice, a second otlice, anoperators position at the first otlice, a called station at the secondollice, means including automatic switching mechanism for connecting thecalled station with the operators position, a source of alternatingcurrent, means for transmitting impulses from said source, eleetromagnetic means energized by said alternating current impulses foractuating said automatic switching mechanism, means for givingsupervisory signals back over the line to the operator, and meansresponsive thereto at the operators position.

4. In a telephone exchange system, a first ofiice, a second oflic-e, aline extending between the otfices, an operators cord circuit at thefirst otlice adapted for connection with said line, an automaticswitching means at the Second oflice, a source of alternating current,means for transmitting an impulse from said source over the line when itis connected with the cord circuit. electromagnetic means responsive tosaid. impulse for pre paring the automatic switching means for thereception of directive impulses ctrom said source, and means fortransmitting directive impulses from said source over said cord circuitand connected line for actuating said electromagn-i-itic means tocontrol the setting of said autoi'nat-ic switching means.

in a telephone exchange system, subscribers stations, a source ofalternating current of a single frequency, switching means. fortransmitting series of current impulses from said source, a tuned relayincluding an inertia element and responsive to said im pulses, and meanscontrolled by said inertia element for establishing connection with asubscribers station corresponding; to the combination of impulsestransmitted.

6. In a switching system, sources of directand alternating currents, afirst circuit provided with means for controlling said currents, asecond circuit including); automatic switching means and adapted to bemanually connected to said first circuit, and means at said secondcircuit responsive to said direct and alternating currents toettectresponse o't said switching means for extending the secondcircuit.

7. In a telephone exchange system, a switching system including a, linecircuit, calling and called stations, alternating current receivingmeans, means for applying; alternating currents to said line, switchingmeans controlled by said receiving means in response to said alternatingcurrents to join said stations, a direct current source associated withthe line during the joining of the stations. means tor reversing thecurrent from said source on the line when the stations are joined, andmeans actuated thereby to disable the receiving means.

8. In a telephone system, a toll line, a cord circuit adapted to beconnected to one end of the toll line, automatic switching meansassociated with the opposite end of the toll line, means ope 'ated tosupply an impulse of alternating current to said toll line when the cordcircuit is connected thereto, means responsive to said impulse toprepare said automatic switching means for actuation to extend the tollline, and means for transmitting directive impulses 0t alternatingcurrent over said cord circuit and the toll line to operate saidswitches.

9. In a telephone system, a toll line, automatic switching means, meansincluding devices for transmitting one impulse from an alternatingcurrent source to prepare. said switching means for directive operation,and means for transmitting directive impulses from said alternatingcurrent source to actuate said automatic switching means to extend thetoll line accordingly.

10. In a telephone system, a toll line, a cord circuit adapted to beconnected thereto, automatic switching means associated with said tollline, means including devices for transmitting one impulse from analternating current source to prepare said switching means for directiveoperation, and means for transmitting an impulse consisting of currentfrom plurality oi alternating current sources to the cord circuit. meansassociated with said cord circuit for indicating the reception of saidimpulse, and means for transmittingdirective impulses from said firstmentioned alternating current source to actuate said automatic switchingmeansto ere tend the toll line accordingly.

ll. in a. telephone system, a toll line, a cord circuit, automaticswitching means, means Olwl'tii'lllg to supply a current impulse to saidtoll line when the cord circuit is connected to the toll line, and meansresponsive to said current impulse to prepare the automatic switchingmeans for the reception of directive impulses, and means fortransmitting directive impulses to said switching means to actuate thesame to extend the toll. line accordingly.

12. In a telephone system, a line, auto matic switching means, analternating current source, means for transmitting impulses therefrom,means responsive to a preliminary impulse to prepare the automaticswitching means for the reception of directivc impulses, meansresponsive to subsequent impulses to control the. automatic switchingmeans to extend the line accordingly, and means for disabling the lastmentioned means when the line is extended.

In witness whereof, I hereunto subscribe my name this 8th day ofNovember A. D.,

HENRY W. ONEILL.

Hit)

